1. Field of the Invention
The present invention relates to a liquid jetting apparatus, a piezoelectric actuator, and a method for producing the liquid jetting apparatus.
2. Description of the Related Art
Conventionally, as a configuration of piezoelectric actuators used for various purposes, there has been known such configuration in which a wiring substrate is connected to a surface electrode of a piezoelectric element to supply a signal for driving the piezoelectric element.
Conventionally, there have been known piezoelectric actuators provided for an ink-jet head to jet liquid droplets. Such ink-jet head is provided with a channel unit (channel structure) in which ink channels including a plurality of nozzles are formed, and a piezoelectric actuator provided for the channel unit. Further, the piezoelectric actuator has a piezoelectric layer, and a plurality of individual electrodes formed on a surface of the piezoelectric layer to correspond to the plurality of nozzles, respectively.
A flexible wiring substrate (COF) is connected to the plurality of individual electrodes of the above piezoelectric actuator. A driver IC is mounted on the wiring substrate, and a plurality of wires connected with the driver IC are formed in the wiring substrate. Further, the wiring substrate is provided with a plurality of contact points (substrate-side contact points) corresponding to the plurality of individual electrodes respectively, and these plurality of contact points are connected to the driver IC via the aforementioned wires. Then, the plurality of individual electrodes on the surface of the piezoelectric layer are connected to the plurality of contact points of the wiring substrate, respectively, by bumps of conductive resin including a metallic material and a thermosetting resin. By virtue of this, a drive voltage is applied to each of the plurality of individual electrodes from the driver IC mounted on the wiring substrate.
In a conventional piezoelectric actuator, the electrodes (the individual electrodes) are formed on the surface of the piezoelectric layer, the contact points (the substrate-side contact points) are formed on the wiring substrate, and it is configured such that the individual electrodes of the piezoelectric layer and the contact points of the wiring substrate are connected by the bumps of conductive resin. Therefore, the connection structure between the wiring substrate and the piezoelectric layer (piezoelectric element) is complicated. Further, it is necessary to not only form the electrodes on the piezoelectric layer but also form the contact points on the wiring substrate. This accordingly increases the number of production processes, thereby suffering disadvantage in terms of cost.